No 3 (2025)
Materials science in mechanical engineering
CARBON SHAPE TYPE AND HEAT TREATMENT EFFECT ON THE STRUCTURAL CHARACTERISTICS OF THE CARBIDE PHASE IN THE COMPOSITE MATERIAL AL-5%CU-10%TIC OBTAINED BY THE SHS METHOD
Abstract
The paper presents the analysis of carbon shape type effect (carbon black and multilayer carbon nanotubes) on the morphology and distribution of the titanium carbide phase in the composition of a composite material obtained by self-propagating high-temperature synthesis Al-5%Cu-10%TiC, further subjected to heat treatment as thermohardening and artificial ageing. It is shown that both carbon modifications make it possible to synthesize a highly dispersed carbide phase with dimensions up to 800 nm from its inception. However, during the subsequent heat treatment of samples obtained on the basis of a charge with nanotubes, a decrease in the dispersion of titanium carbide particles to 2 microns and an increase in their degree of agglomeration is observed, resulting in a decrease in the hardening effect of ageing. Based on the analysis of the mechanism of carbide formation, it is suggested that as a result of high-speed capillary spreading of titanium over the surface of carbon particles within synthesis, the formed particles inherit the geometry of the original carbon shape. In this regard, when using carbon black, the synthesis of rounded titanium carbide particles is advantageous, and in the case of nanotubes it is cylindrical particles that make the better of. Differences in morphology, in turn, determine the varying degree of self-diffusion during subsequent heating, which contributes to more significant changes in the dispersion and distribution of the carbide phase in samples synthesized on the basis of nanotubes. The obtained results lead to a conclusion that the type of carbon shape has a significant effect on the structural characteristics of the carbide phase and give reason to recommend the use of carbon black, which is characterized by a lower cost.
Science intensive technologies in mechanical engineering. 2025;(3):3-10
3-10
Additive technologies and laser processing
MATERIAL CONSUMPTION CAPACITY AS A TECHNOLOGY INDEX FOR MANUFACTURABILITY IN THE PRODUCTION WHEN USING ADDITIVE TECHNOLOGY METHODS
Abstract
Ways of characterization for material consumption capacity of products manufacture using additive technologies (AT) is viewed in the article. The research conducted on this topic by various authors in relation to additive manufacturing is discussed. The methods of calculating the material consumption capacity are analyzed, conclusions concerning previous studies are drawn. The calculations of the material consumption capacity for a full set of components were made using two different techniques – machine working and the AT method. The material utilization ratios are found, the cost of materials spent on the manufacture of parts by machine working and using AT technique is calculated. A comparative analysis of the cost of raw material was carried out. Conclusions are drawn about the impossibility of an unambiguous preference for the choice of manufacturing parts based on such criteria as the material utilization ratio. It has been concluded that further research of the manufacturability of products using AT is quite indispensable.
Science intensive technologies in mechanical engineering. 2025;(3):11-18
11-18
Science intensive technologies in machine assembly
IMPACT ANALYSIS OF TEMPERATURE, MASS, AND OSCILLATION AMPLITUDE ON THE ASSEMBLY OF A THREADED FASTENING USING ULTRASOUND
Abstract
A number of works devoted to ultrasonic assembly and disassembly have been analyzed, and their disadvantages have been identified, in particular, lack of attention to the issue of multifactorial nature of the influence on assembly using ultrasound. Based on the analysis of the sources, the factors that can significantly affect the assembly process of threaded fastenings are determined. They are temperature, mass of the assembled fastening, as well as the amplitude of vibrations. The results showed that increasing the mass of the assembled threaded fastening increases the effectiveness of ultrasound application. The results also showed that increasing or decreasing the temperature has virtually no effect on the assembly efficiency, which is confirmed by statistical processing, which shows a small relationship between the response and the factor. At the same time, the use of ultrasound, depending on the temperature, affects the spread of the obtained values within a single point – the values obtained vary in the range of 5 % at average temperatures and in the range of 10% at boundary values. The results of the multifactorial experiment confirmed the nature of the influence of the oscillation amplitude, mass and temperature of the assembled fastening, revealing the importance of the amplitude and mass factors, while the temperature factor can be neglected due to its minor influence. The results of the multifactorial experiment were processed using two different methods, as a result of which similar dependencies were obtained, which, in turn, confirms the high reliability of the obtained results.
Science intensive technologies in mechanical engineering. 2025;(3):19-28
19-28
Surface layer quality, contact interaction, friction and wear of machine parts
ESTIMATED FRICTION AND LOAD CAPACITY COEFFICIENTS FOR A MODIFIED RADIAL BEARING DESIGN UNDER A TURBULENT CONDITION FRICTION
Abstract
The effect of a true viscous lubricant in a radial sliding bearing coated by polymer having a specialized groove on the shaft surface is studied. The developed computational model based on the equations of fluid motion and the equation of continuity allows for a deeper understanding of the dynamics of the lubricating layer and its interaction with the working surfaces. Special attention is paid to the geometric features of the groove, which affect the pressure distribution inside the bearing. The integrated use of a polymer coating and a groove ensures uniform load distribution, which increases the load capacity of the system. Numerical calculations show that the use of a polymer coating reduces friction coefficient and contributes to the efficient operation of the lubricant in turbulent conditions. Experimental validation of the model was carried out under various load conditions and rotational speeds, which made it possible to compare theoretical calculations with experimental results in a high-quality way. The analysis showed a high degree of agreement between calculations and experiment, confirming the reliability of the proposed model. The results obtained prove the necessity of design solutions, such as a combination of polymer coatings and grooves for improved bearing performance.
Science intensive technologies in mechanical engineering. 2025;(3):29-37
29-37
ANALYSIS OF CONTACT MECHANICS OF A BANDAGE AND SUPPORT ROLLS OF ROTARY KILNS
Abstract
The basics of the design of rotary kilns, widely used in the processing and preparation of various raw materials, are described. It is shown that the weak point of the rotary kilns design is the support rollers, which carry the entire load of the kiln and are initially made of less durable steel than a bandage being in contact with them. In fact, the design itself provides for the possibility of periodic replacement of the «miscellaneous part», which is a support roller. However, for an operator, any downtime of equipment leads to economic losses. Therefore, the goal has been formulated: to increase the durability of the support rollers avoiding a significant change in the kiln design. For this purpose, initially, from the point of view of contact mechanics, the basics of the interaction of the surfaces of the support roller and the bandage of a rotary kiln have been studied. Calculation models for various contact options of these parts have been given. The force model of contact between the surfaces of the support roller and the bandage has been studied. The maximum normal and tangential stresses in the contact zone, at its boundary and beyond have been determined. At the same time, complex processes occur in the contact area of the roller and the bandage surfaces, in particular, micro-slipping and sliding, due to the difference in the diameters of the rotating bodies and the difference in the level of their mechanical properties. Micro-slip is one of the sources of fretting wear. However, the most significant wear occurs as a result of mechanical interaction and changes in the structure of the surface layer with the gradual accumulation of various kinds of defects in the crystalline structure caused by plastic deformation of the surface layer of the contacting parts. It is shown that not only the mechanical and operational properties of the material for their construction, but also the displacement of the contact spot during kiln operation have a significant effect on the wear process of the support rollers. The displacement can be angular or linear, and in real conditions it is most often combined, it is caused by the thermal expansion / compression of the metal structure and the operating conditions of the rotary kiln.
Science intensive technologies in mechanical engineering. 2025;(3):38-48
38-48